Legacy promotion removal: elasticsearch changeset removal

Removing the indexing of changeset products, repos, packages
and errata.  This is needed; otherwise, creating and applying
changesets will fail.
Merge pull request #2519 from bbuckingham/delete-legacy-promotion

Legacy promotion removal: elasticsearch changeset removal
Legacy promotion removal: Removing environment_product model

Removing environment_product model since products are no longer being
promoted. Instead, now repos join environments and products directly.